: What would happen if.....

12-05-05, 01:33 PM
I am about to order new tires to replace my bald runcraps.

Im thinking 275/40/18 in the rear (26.66" diameter) and 255/40/18 in the front (26.03 diameter). In my opinion wouldnt having a less diameter in the front make more sense (255/40/18) than putting a greater diameter (stock 245/45/18 or 26.68" diameter) when putting them in combination with the 275 or 26.66 diameter. I mean wouldnt I get a little more rake to the look of the car. What would be the downside or bad effects from doing the 26.66 in rear and 26.03 in front???

BTW I DO PLAN ON LOWERING THE CAR, so please take that into consideration. And these are the stock rims.

Thanks to truk for the little chart (I hope it wasnt copyrighted):shhh:
245/45/18 = 26.68 " diameter (STOCK)
255/45/18 = 27.04 " diameter
255/40/18 = 26.03 " diameter
265/45/18 = 26.39 " diameter
265/40/18 = 26.35 " diameter
275/45/18 = 27.74 " diameter
275/40/18 = 26.66 " diameter
285/40/18 = 26.98 " diameter
285/35/18 = 25.85 " diameter

12-05-05, 01:47 PM
How much difference will the car allow? I have no idea, but at some point I think stabilitrac and the anti-lock brakes won't be happy.

12-05-05, 02:00 PM
Its half an inch.

12-05-05, 02:41 PM
John at CCW has tried this combo: 255F & 275R and was not successful at getting it to work... ABS and Stabilitrac issues. He said he worked with GM and they tried to reprogram the PCM (BCM actually) and could not get it to work.

0.6" is too big a diameter diff front-to-rear. Less is ok... so you could run 255/40F and 265/40R.

And when choosing tire sizes you cant consider 26.68 as larger than 26.66... it's considered the same size tire... 0.01" is the thickness of a piece of paper.

12-05-05, 10:48 PM
Dreamin -

Not much paper is only .01" thick...but some is :D